Computer based education (CBE) systems have been developed over the last 20 years or so to a relatively high degree of sophistication. Although employing computer technology, CBE systems have evolved a set of unique demanding requirements.
In the course of using CBE equipment, the user typically has available an electronic display (such as a CRT) and a keyboard; information may be presented to the user in the form of text and/or graphical matter (akin to a textbook) and the user, via the keyboard, can respond by indicating he has completed his review of the material being presented and is ready for presentation of additional material, he can manifest his understanding of the material by responding to questions and the like. In this scenario speed is obviously important, the user does not want to sit idly by while the machine spends many seconds or more in presenting a new display, or while the machine responds to his keyboarded operations. In a short hand fashion, we can identify some of the criteria for successful interaction; fractional second response and correspondingly fast screen displays and the ability to handle presentations mediated by large, complex programs involving elaborate displays.
Insofar as we are presently aware, the characteristics of CBE have required that it be implemented by a combination of equipment including a relatively large main frame computer and a plurality of terminals (one for each user) which includes both a display and keyboard. The reasons for implementing CBE system using this type of equipment was originally because it was the only available equipment, that is, 20 years ago all computers were what is now termed main frame computers, and only terminals were available for communication with the main frame computer. Since that time, technology has evolved making available minicomputers and even microprocessors; however, for a number of reasons CBE systems is, in the main, not implemented employing this equipment.
The size of the programs which the computer usually executes to provide CBE is one reason which has so far detracted from the applicability of microprocessors since only recently have microprocessors been available with memory capacities in excess of 64 K bytes and that is, even today, considered inadequate. Typical programs require 100 K bytes for the program itself and associated support routines; many require much more memory. In addition, there has been a desire to provide a central repository for maintaining records about the CBE users, their levels of proficiency, lessons completed, etc. While there have been CBE uses with processors akin to microprocessors (and associated with floppy disks for program material storage) this arrangement has proven to be inadequate for at least the inability to centralize user records. Another difficulty exhibited by the microprocessor type equipment is the mechanical nature of the floppy disks and the concomitant delays in transferring program material from the floppy disk to the RAM. Although these delays are relatively short, delays are expected, and that is, from the user's point of view, undesirable. For most CBE purposes the response time should be measured in tenths of seconds; a standard which the floppy disk drive cannot be expected to meet.
One example of the typical CBE system is the system developed at the University of Illinois under the acronym PLATO. Although specialized equipment has been developed for this system, it exhibits the traditional characteristics of CBE in that it relies on a large main frame computer (the CDC Cyber) driving many (more than one thousand) terminals, however the terminals are relatively "dumb" in that all program execution is effected in the Cyber computer. Communication consists of transmitting to the terminal information necessary to produce a display, and transmitting from the terminal to the computer, the user's keyboard entries. This form of delivery is very limiting since it is difficult to envision a single main frame computer running more than two or three thousand terminals. Such an arrangement is then costly (the two or three thousand terminals must support the cost of the main frame machine) due to machine and communication costs.
We can characterize the centralized or traditional CBE architecture as providing good communications (between the central computer and the terminals), the ability to readily update the user proficiency indication and other data bases, the ability to deliver burst processing (because of the high processing speed of the large central computer), as well as the ability to provide effective management tools (especially because of the centralized data collection capability). On the other hand, in contrast, the stand-alone system (typical microprocessor operating from a floppy disk memory) has poor communications characteristics and as a result, updating a central data base is difficult at best, and finally, because of the independent nature of the stand-alone environment, the management tools are ineffective. On the other hand, the centralized architecture exhibits restricted display and processing speed (since all displays are created and all processing is executed by the single central machine), reliability is a problem since a malfunction in the central machine will bring down the entire system, the system typically exhibits high initial system costs, and annual costs including the communication expenses. On the other hand, the stand-alone architecture provides relatively fast local displays (since the display is created locally), there are no communication costs, any failures are soft failures, since each station is independent of others, and there are relatively low initial costs. An improved system will exhibit the advantages of both the stand-alone and the central architecture while avoiding the disadvantages of both.
Notwithstanding this traditional architecture, it should be apparent that an improved delivery system which did not rely so much on the central computer, and provided distributed intelligence at the users' terminals would be desirable from a number of points of view. Under the present arrangement, the number of terminals which can be driven from a single computer is limited, in the event of a computer malfunction, the entire system (with perhaps a thousand terminals) becomes unusable until the central computer can be repaired and geographic dispersion of terminals carries with it high communication costs.
Accordingly, it is one object of the present invention to improve the architecture of CBE systems to allow less costly geographic dispersion of the terminals. It is another object of the present invention to reduce the dependence on a central main frame computer. It is another object of the present invention to achieve the foregoing objects without at the same time impairing the centralized record keeping function exhibited by traditional CBE system architecture or compromising the fast response time now enjoyed by users.